问题 问答题

工业合成氨与制备硝酸一般可连续生产,流程如下:

(1)在合成氨的反应中,改变反应条件,会使平衡发生移动.如图象表示随条件改变,氨气的百分含量的变化趋势.

当横坐标为压强时,变化趋势正确的是(选填字母序号)______,

当横坐标为温度时,变化趋势正确的是(选填字母序号)______.

(2)如图所示三个容积相同的容器①、②、③,若起始温度相同,分别向三个容器中充入3mol H2和1mol N2,一定条件下反应,达到平衡时各容器中NH3物质的百分含量由大到小的顺序为______(填容器编号)

(3)氨气和氧气从145℃就开始反应,在不同温度和催化剂条件下生成不同产物(如图所示):

4NH3+5O2

4NO+6H2O

4NH3+3O2

2N2+6H2O

温度较低时以生成______为主,温度高于900℃时,NO产率下降的原因______.吸收塔中需要补充空气的原因______.

答案

(1)、工业合成氨为N2+3H2

催化剂
.
高温高压
2NH3 △H<0 增大压强时平衡向右进行,氨气的百分含量增大,

因△H<0,为放热反应,增加温度,平衡向逆反应方向移动,氨气的百分含量减少,故答案为:b,a.

(2)、以②为基准,①外有隔热套,相当于在②基础上加热平衡向逆反应方向移动,氨气的百分含量减少.③是恒压状态,相当于在②基础上加压,平衡向右进行,氨气的百分含量增大.所以NH3物质的百分含量由大到小的顺序为①<②<③

故答案为:①<②<③;

(3)、由图象可知在温度较低时生成氮气.温度高于900℃时,NO产率下降是因为反应4NH3+5O2

4NO+6H2O时放热反应,达到平衡后,升温平衡逆向进行.故产率降低.吸收塔中需要补充空气是增加反应物的浓度,使平衡向正向移动,进一步与NO反应生成硝酸.

故答案为:N2;生成NO的反应为放热反应,升高温度转化率下降;进一步与NO反应生成硝酸.

单项选择题
阅读理解

阅读理解。

     Now, we know that if we do not get enough vitamins, we are at risk of developing a number of

diseases. As a result, vitamin supplements (补品), though expensive, are popular with people who

worry that they are not getting enough vitamins from the foods they eat. But contrary to what many

people think, medical experts have found little evidence that most supplements do anything to improve

health or protect against disease.

     In fact, medical experts warn that taking too many of some vitamins can be harmful. For example,

too much vitamin E can cause bleeding. People should discuss what vitamins they take with their

doctors, as some vitamins can produce harmful side effects when mixed with medicines.

     Experts, however, do say that sometimes vitamins can help prevent disease. People who know they

lack a particular vitamin should take vitamin supplements. Some older adults, for example, may not have

enough vitamin B-twelve. This is because, as people get older, their body loses its ability to take it from

foods. Also, people who spend much time inside may need some extra vitamin D as the skin makes this

vitamin from sunlight.

     Different vitamins are found in different foods. Vitamin A is found in fish liver oil. It also is in the

yellow part of eggs. Sweet potatoes, carrots and other darkly colored fruits and vegetables contain

substances that the body can change into vitamin A. Vitamin B-twelve is found in green leafy vegetables

and other foods, like fruits. Vitamin K can be found in pork products.

     In fact, for most people, a balanced diet can ensure enough of the vitamins our bodies need. So, it is

important for us to eat a mixture of foods every day to ensure that we get enough vitamins our bodies

need.

1. What is probably talked about before this passage?

A. How many vitamins a person's body needs.  

B. How many vitamins some foods contain.

C. The benefits that vitamins bring to our health.

D. What people should do to stay healthy.

2. Vitamin supplements are popular with people because ________.  

A. people mistakenly think that they are good for their health

B. they contain more vitamins than the foods people eat

C. food does not provide enough vitamins people need

D. people fear that a lack of vitamins will lead to disease

3. From the passage, we can learn that medical experts advise people _________.

A. never to take any vitamin supplements  

B. to depend only on food for their vitamins

C. not to take any vitamins together with medicines

D. to consult doctors before taking vitamin supplements

4. For people who lack Vitamin B-twelve, they can eat more from _______.

A. sweet potatoes  

B. green leafy vegetables  

C. pork products